Patterns of pathogenic microbial contamination of handwashing sinks change over time following new installations

Environmental contamination of handwashing sinks and drains can negatively impact hand hygiene practices and facilitate pathogen transmission. This study determined what contaminations occurred after sink and drain installation, when and for how long, as well as differences in contamination patterns depending on the purpose of sink use in a non-outbreak setting.

The study was conducted from November 2022 to October 2023. Two new sinks and drainpipes replaced the existing sinks in a general internal medicine hospital ward staff station for use before and after patient care. A third single sink and drainpipe was installed in the staff break room for non-medical use. Bacterial samples were collected from the water tap, sink basin, drain and drainpipe by swab or sponge on days 1 (installation day) and 3 in week 1, in week 2 and monthly thereafter. The cleaning staff members were responsible for cleaning the sink basins and drains daily with detergent.

Within the first week after installation, pathogenic microbial contamination (Pseudomonas aeruginosa, Citrobacter freundii and Stenotrophomonas maltophilia) of drainpipes was observed in both the staff station and the break room. Taps were contaminated 2 weeks after installation at the staff station. The contamination cleared but recurred repeatedly until the 12-month point. Pathogens in drainpipes persisted for longer in the staff station than in the break room.

The intermittent microbial contamination patterns of the handwashing sinks changed over time following their installation. Pathogenic microbes persisted, especially in drainpipes and in sinks used for clinical purposes, as opposed to non-clinically used sinks.